The present invention is directed toward bicycle disc brakes, and more particularly toward a retaining structure for a friction pad and plate assembly of a caliper of a disc brake.
Disc brakes are being included on more and more bicycles as consumers are ever increasingly demonstrating a preference for disc brakes over conventional rim brakes such as caliper brakes, cantilever brakes and side pull cantilever brakes. Disc brakes typically include a friction pad and plate assembly which is operatively associated with a caliper of the disc brake assembly. More particularly, the caliper typically includes a cavity configured to receive a disc of the disc brake assembly, with the cavity having a mouth at a leading end and a pair of opposing recesses configured to receive a pair of the friction pad and plate assemblies on opposite side of the disc with the caliper further having a drive advancing the pad of at least one of the friction pad and plate assemblies into contact with the disc along an advancement axis. The friction pad of the pad and plate assembly is intended to wear with use and the pad and plate assembly must be replaced from time to time. Thus, a suitable retaining structure allowing for replacement of the pad and plate assembly is used. This general structure is widely used in to industry.
There are a number of known retaining structures for friction and plate assemblies. Some of these require special tools to remove the friction pad and plate assembly. In other instances, the pad and plate assembly snap into place by being advanced along an advancement axis into engagement with a pressure foot. While this later structure has the advantage of not requiring any tools to install and remove the friction pad and plate assembly, it does not adequately secure the pad and plate assembly to prevent unintentional disengagement or misalignment of the pad and plate assembly when the disc is not disposed between opposing recesses receiving the pad and plate assemblies. Thus, there remains a need to provide a retaining structure for a pad and plate assembly that allows the pad and plate assembly to readily removed and replaced without tools while securing the pad and plate assembly when installed against unintentional dislodging.
The present invention is directed toward overcoming one or more of the problems discussed above.
The first aspect of the present invention is a retaining structure for a friction pad and plate assembly of a caliper of a disc brake assembly. The caliper of the caliper disc brake assembly includes a housing with a cavity configured to receive a disc of the disc brake assembly. The cavity includes opposing recesses configured to nest first and second friction pad and plate assemblies on opposite sides of the disc. A drive within the caliper housing advances the pad of the first friction pad and plate assembly into contact with the disc along an advancement axis. The retaining structure includes a pad retention clip attached to the housing within the cavity. The pad retention clip defines an elongate, track extending along the advancement axis. A retention tab on a plate of the first friction pad and plate assembly is configured to snap fit with the pad retention clip and to move along the advancement axis within the elongate track as the first friction pad and plate assembly is advanced along the advancement axis by the caliper drive. The retention clip preferably extends along the advancement axis substantially the same distance as the cavity mouth. Each plate of the first and second friction pad and plate assemblies has a retention tab and both the first and second pad and plate assemblies are snap fit into the same retention clip on opposite sides of the disc. The retaining structure preferably further includes a pressure foot associated with the caliper drive abutting a back side of the plate of the first pad and plate assembly opposite the pad. A keyed engagement structure between the pressure foot and the back side of the plate is brought into engagement by advancing the pad and plate assembly toward the pressure foot along the advancement axis with the keyed engagement structure, when engaged, preventing release of the pad and plate assembly from the pad retention clip by movement of the pad and plate assembly transverse the advancement axis. The plate of the pad and plate assembly may be made of a ferrous material and the pressure foot may includes a magnet to releasably attach the plate to the pressure foot.
Another aspect of the present invention is a backing plate of a pad and plate assembly. The pad and plate assembly is for use with a caliper of a disc brake assembly, the caliper having a housing with a cavity configured to receive a disc of the disc brake assembly. The cavity mouth has a leading end and a pair of receiving recesses configured to nest a pair of backing plates on opposite sides of the disc. The caliper drive advances the friction pad of at least one of the pad and plate assemblies into contact with the disc along an advancement access. A pad retention clip is attached to the housing within the cavity opposite the mouth of the cavity. The pad retention clip has a pair of retaining legs opening towards the mouth. The backing plate consists of a body having a leading edge and a trailing edge disposed along an advancement access. A retention tab is on the leading edge of the body that has oppositely extending protrusion dimensioned to snap fit between the retaining legs of the pad retention clip by advancing the body along the engagement access and engaging the pad retention clip with the retention tab. The backing plate may further include opposing side edges extending between the leading and trailing edges with the opposing side edges mating with corresponding side walls of the cavity recess to enable sliding movement of the backing plate along the advancement access within the cavity. An elongate handle may extend from the body along the trailing edge of the body. Preferably a structure is provided on the handle for enhancing gripping of the handle. The drive may further include a pressure foot abutting a backing plate, with the pressure foot having a post extending along the advancement axis. With this structure, the backing plate further comprises a leading surface and a trailing surface, with the trailing surface having a receptacle for receiving the post.
Yet another aspect of the present invention is a method of releasably attaching a friction pad and plate assembly to a caliper of a disc brake assembly. The caliper has a housing with a cavity configured to receive a disc of the disc brake assembly. The cavity includes a mouth at a leading end for receiving first and second pad and plate assemblies on opposite sides of the disc received therein. A drive within the housing advances the pad of the first pad and plate assembly into contact with the disc along an advancement axis. The method includes providing a releasable snap fitting between the plate of the first friction pad and plate assembly and a wall of the caliper housing cavity. The releasable snap fitting, when engaged, permits movement of the pad and plate assembly along the advancement axis and resists movement of the pad and plate assembly along an engagement axis transverse the advancement axis. The method further includes providing a keyed fitting aligned along the advancement axis between a backside of the plate opposite the pad of the pad and plate assembly and a pressure foot associated with the caliper drive. The keyed fitting, when engaged, prevents movement of the pad and plate assembly along the engagement axis. The friction pad and plate assembly is advanced within the cavity along the engagement axis to engage the releasable snap fitting and then advanced within the cavity along the advancement axis to engage the keyed fitting.
Yet another aspect of the present invention is a backing plate of a pad and plate assembly for use with a caliper of a bicycle disc brake assembly. The backing plate includes a body having a leading planar surface for attachment to a brake pad. A handle is attached to and extends from the body. A structure is provided on the handle for enhancing gripping of the handle.
The retaining structure for a friction pad and plate assembly of the present invention allows for quick and easy installation and removal of the friction pad and plate assemblies. The structure also provides for secure engagement of the pad and plate assembly to the caliper. Once installed, inadvertent dislodging or misalignment of the pad and plate assembly with the disc removed is highly unlikely. This is particularly important when a wheel of the bicycle is removed, such as when the bicycle is attached to certain carrying racks. Notwithstanding the sure engagement, the pad and plate assembly can be quickly and easily disengaged from the caliper without tools by a simple two-step movement, first along an advancement axis and then along an engagement axis. The retaining structure consists of a minimum number of parts which can be inexpensively manufactured and readily assembled.